2,6-Diamino-3,5-dinitropyrazine-1 -oxide (LLM-105) was discovered at Lawrence Livermore National Laboratory in 1994. LLM-105 is a thermally stable, insensitive molecule with a crystal density of 1.918 g/cc and a decomposition point of >350° C. There have been several reported syntheses of LLM-105, most of them proceed through the intermediate compound, 2,6-diamino-3,5-dinitropyrazine (ANPZ), which upon oxidation with trifluoroacetic peracid yields LLM-105. The most attractive synthesis to date involves the nitration of 2,6-dimethoxypyrazine to 2,6-dimethoxy-3,5-dinitropyrazine followed by amination with ammonium hydroxide to yield ANPZ, and oxidation with trifluoroacetic acid and 50% H2O2. This gives LLM-105 in high yield that is contaminated with 3-10 % ANPZ. Over the years this synthesis has been refined and optimized to give LLM-105 in a 65% overall yield from 2,6-dichloropyrazine or 2,6-dimethoxypyrazine. The separation of ANPZ from LLM-105 in these mixtures has been very difficult and obtaining pure LLM-105 has been problematic.
The synthesis of DAPO was reported previously by the hydrogenation of 2-amino-6-hydroxaminopyrazine-1-oxide (AHAPO) in low total overall yield. The published procedure involved dissolving AHAPO in AcOH and treating it with H2 at 45 psi at room temperature for 1 hour in the presence of Adam's catalyst (PtO2). DAPO is a stable white solid with a melting point of 294-295° C.
The synthesis of LLM-105 by the nitration of DAPO was described previously in a patent application and later published by Bellamy and Golding in the Central European Journal of Energetic Materials in 2007.
What is therefore needed is a way to synthesize pyrazines such as DAPO in good yields and LLM-105 in a more efficient and inexpensive manner.